Exhaust system for marine propulsion device

ABSTRACT

Disclosed herein is a marine propulsion lower unit which is arranged to afford exhaust gas discharge during forward drive through a discharge outlet at the rear of a propeller hub, and when operating under conditions other than in forward drive, to provide underwater exhaust gas discharge upstream from the exhaust gas discharge outlet at the rear of the propeller.

United States Patent Inventor William J. Shimanckas Waukegan, Ill. Appl. No. 833,826 Filed Jan. 21, 1969 Division of Ser. No. 627,116, Mar. 30, 1967,

Pat. No. 3,407,051. Patented Jan. 19, 1971 Assignee Outboard Marine Corporation Waukegan, 111.

a corporation of Delaware EXHAUST SYSTEM FOR MARINE PROPULSION DEVICE 8 Claims, 8 Drawing Figs.

U.S. Cl. 115/34, 1 15/17 Int. Cl. B63h 21/14, B63h 1/20 FieldofSearch 115/17, 18, 34, 35; 74/378 [56] References Cited UNITED STATES PATENTS 1,844,386 2/1932 Harris et al. 74/378UX 2,718,792 9/1955 Kiekhaefer 1l5/34X 2,093,357 9/1937 Harper 115/17 FORElGN PATENTS 292,014 5/1916 Germany 115/17 Primary ExaminerTrygve Blix Attorney-Wheeler, Wheeler, House and Clemency ABSTRACT: Disclosed herein is a marine propulsion lower unit which is arranged to afford exhaust gas discharge during forward drive through a discharge outlet at the rear of a propeller hub, and when operating under conditions other than in forward drive, to provide underwater exhaust gas discharge upstream from the exhaust gas discharge outlet at the rear of the propeller.

A TEU JAN 1 919m 3,656; 041

SHEET 2 [1F 2 .1 EXHAUST SYS TE-M .FORMmINEPROPULSION DEVICE This applicationis a'divisionof my copending application Ser. No. 627,116; filed'M-ar. 30; 1967 and-now U,S: Pat.No. 3,467,05 Lfiicd Sept, 16; 1969i BACKGROUND OF THE- INVENTIQN In thepast, marine propulsion devices with; lower units arrangedto affordexhausfgas'discharge throughthe propeller hub and into thepropeller-slip. stream. have been'commonly used; Such; arrangements suffer from the disadvantage that, during jreverse operation; the exhaust 'gases are: discharged into the water throughwwhichthe propeller is biting,.thereby tending to create conditions of ventilation"? or cavitation andreducingtheefficiencyof the propeller.

SUMMARYOF-INVENTION DRAWINGS FIG. 1' is a fragmentary view; partially in section, of a marine'propulsion deviceembodying-yarious of the features of the invention;

FIG-121$ an 'enla'rged. fragmentary view, partiall'y. in-section, of;thepropulsiondeviceshown-in FIG. ljwith-Zcertain components in another position;

FIG-3 is a fragmentary view, partially in section, of another embodiment of the-invention whicl'ris similar to the embodimentshownin FlGS. t and 2;;

FIG. 4 'is a fragmentary view, partially insection, of the deviceshownin FIG.% 3 with certain components. in another position; i

FIG-515.8 fragmentary view, partially inzsectionrof another marinepropulsion device embodying variousof the features of the invention;

FIG. 6 is a fragmentary view, partially in. section,nof thedevice shown in-FIGwSiwith certain components in different positions; t v

FIG. 7 is a fragmentary view, partially in:section',-of another marinepropulsion device embodying variousof thefeatures of the invention; and

FIG. 81isa fragmentary; view, partially: in section, of the deviceshown. in.- FIG. 7' with certain components in different positions.

GENERAL DESCRIPTION Shown" in FIG; I. is a fragmentarily 4 illustrated A marine propulsion device '11 includinga lower-unit llwhich} can be I vertically and horizontallyswingablymountedto a boathull.

As. is-conventional, the: lower 1unit l3 includes a drive shaft hbusing ISIhaVing'at the lower endthereof, a gear case 17 in which'lthere. iszrota tablygmountedla propeller shaft 19. The lower. unit also conventionally.includes an exhaust. gas

passageway 23which"extends throughithe drive shaft housing 15. and terminatesyat the rearward end: of the gear case, in anexhaustgasdischarge port,Zithroughwhich extends the propeller shaft 119: As is conventional, thepropeller shaft can be. connected for forward-drive, rearward drive; and neutral bya clutch mechanism (not shown Carried on the propeller shaft'l9forrotation therewith is apropeller 27'havinga hub 29fand a pluralityofblades-Slimountdonwthe hub, each blade having-a forwardface 31a and a rearward face 31b. As is wardend; with ane inlef34 and; it" rearward end, with a discharge openingoroutlet 35 rearwardly. of the propeller blades 31. The exhaust gas duct 33 islocated inpositionfor communication of the inlet 34 with theexhaustgas port 25 to afford exhaust gas flow from' the engine (not shown) through 'the exhaustgas passageway 23 in the lower unit'l3; and

through the exhaustgas duct '33 *in the propeller 27 for exit through the rearwarddischarge opening 35:

Inaccordance withtheinvention, thereis provided means for affordingmnderwater exhaust-gas discharge forwardly of the rear. face of the propeller blades when the propeller shaft. is

operating in-rear-warddrive condition- Whilevariousarrangements can be-employed, in'thedisclosed constructions there is providedmeans affording axially shiftingof thepropeller relative tothe dischargeport between a positionwhereinthe lower unit discharge port and the inlet arcin direct communication andv a second position-wherein the discharge port 'and an inlet are inspaced relation'to each other.

Also in accordancewith the invention, in the embodiment as shown in: FIG. 1, themounting of thepropeller 27 on:the propeller shaft 19 issuchas to freely afford axial movement of the propeller 27 on the propeller-shaft l9' relative to the dischargeport 25 betweena first position affording direct communication of the'exhaust gas duct 33 with the discharge port ZS-anda second more rearwardlylocated position (See FIG. 2) in whichthepropeller hub 29 is spaced from the discharge port -to afford an annular openingoroutlet 37 facilitatingexhaust gas discharge forwardly of the discharge opening'35 at the rearof-the propeller hub 29.

Accordingly, when the propeller 27 is driven for forward propulsion, the .water reaction will displace the propeller 27 forwardly onthe propeller shaft-19"-until the exhaust gas discharge port 25 and'the forward portion of the-propeller. hub 29 are in partially telescopic relation to each other (FIG, I), thereby. affording direct communication. Under suchcircum stances, exhaust gas is discharged through the discharge opening 35 into the. propeller slip. stream rearwardly of the propeller blades 31. Howevenwhen the propeller shaft 19 is rotated to provide rearward drive, thewater reaction displaces thepropeller 27 rearwardly on the propeller shaft 19 to providean annular exhaust gas outlet 37 (FIG. 2) forwardly of the propeller blades 31- between the propeller hub 29 and the exhaust gas dischargeport 25, therebyaffording exhaust gas discharge into the propeller slip stream and not through they discharge opening35 into the water into which the propeller 27'bites during rearwarddrive conditions.

Various means can be employed .to afford axial shifting of the propeller 27 on the propeller shaft I9,- whilealso affording v rotary driving connection between thepropeller shaft 19-and thepropeller 27. In the disclosed construction, such. means is in the form -of complementary splines 39 on each of the propeller shaft 19 and the sleeve portion 30.

Means are provided for limiting travel of thepropeller 27 on the propeller shaft 19. While-various means can be employed, in the disclosed construction, such means is in the form of stops axially spaced at a distance greater thanthelength of the hub to. afford withdrawal of the propeller hub 4 from telescopic relationtto discharge port 35 and-to providethe annular outlet 37'with sufficient length to facilitate exhaust gas discharge when in reverserSpecifically, the propeller shaft is'provided with: a annular shoulder or stop 41 which is located forwardly of thesplines 39and-which is engaged by the sleeveportion 30 to limit forward propeller movement and to establish-the forward drive position of thepropeller-27'.

Rearward propeller movementis limited by a washer or stop 43.,which is seated against a shoulder 45 on the propellershaft l 19. by a nut 47 and which .extendsradially to afford engagementby the sleeve-portion'30and thereby establish the rearward drive position of thepropeller 27.

The propeller hub 29 and the discharge port 25 are provided with cooperating means for preventing exhaust gas escape therebetween when in telescopic relation. While various arrangements can be employed, in the disclosed construction, such means is in the form ofa labyrinth seal formed by a series of facing annular grooves 51 on the internal wall of the discharge port 25 and on the external wall of the forward periphery of the propeller hub 29.

If desired, means can be provided for closing the exhaust gas discharge opening 35 when the propeller 27 is displaced to its rearward position to preclude exhaust gas discharge from the opening 35. Thus, in the construction shown in FIG. 3, the washer 430 extends radially outwardly for engagement with the outer annular wall of the hub 29, thereby closing the opening 35 when the propeller 27 is in its rearwardmost position. It is noted, that in the arrangement shown in FIG. 4, when the propeller 29 is in its forward drive position there is provided an annular exhaust gas discharge area or outlet 53 which has a greater axial length than the annular outlet 37 afforded when the propeller 29 is in its rearward drive position.

Other arrangements can also be employed for effecting axial shifting of the propeller relative to the exhaust gas discharge port of the lower unit. For instance, means can be provided for axially shifting the propeller shaft carrying the propeller so as to afford movement of the propeller relative to the lower unit discharge port. In addition, such shifting of the propeller shaft can also be employed to afford shifting of a clutch mechanism. Thus, in the construction shown in FIGS. and 6, there is disclosed a marine propulsion device 111 including a lower unit 113 having an exhaust gas passageway 123 terminating in a discharge port 135. The lower unit 113 includes a gear case 117 into which there extends a drive shaft 157 carrying a drive bevel pinion 159 forming a part of a clutch mechanism 161. Meshed with the pinion 159 are a pair of bevel gears 163 and 165 which are rotatably mounted on a propeller shaft 119 extending through the discharge port 135. Fixedly mounted on the propeller shaft 119 is a propeller 127 with a hub 129, a plurality of blades 131 extending from said hub 129, and an axial exhaust gas duct 133 which extends through said hub 129 and terminates at a rearward discharge opening 135.

In accordance with the invention, means are provided in the gear case 117 for mounting the propeller shaft 119 for rotary movement and for axial movement whereby to rotatably drive the propeller shaft 119, while affording movement of the propeller 129 relative to the lower unit exhaust gas discharge port 125 between a first position (See FIG. 5) associated with forward drive operation wherein the propeller hub 129 and lower unit discharge port 125 are partially telescopically related so as to afford exhaust gas discharge through the propeller hub outlet 135 rearwardly of the propeller blades 131, and a second position (See FIG. 6) associated with rearward or reverse drive operation and located rearwardly of the first position wherein the hub 129 is withdrawn from telescopic relation to the lower unit discharge port 135 to provide an annular exhaust opening or outlet 137 between the lower unit housing 115 and the propeller hub 129. In the disclosed construction, such mounting means comprises a pair of spaced bearings 169 and 171. The bearing 169 is carried by the gear case 117 forwardly of the clutch member 161 and the bearing 171 is carried by a support member 173 located rearwardly of the clutch mechanism 161.

Means are also provided for axially shifting the propeller shaft 119 and, if desired, for coordinating such shifting with operation of the clutch mechanism 161 controlling transmission or rotary power from the bevel gears 163 and 165 to the propeller shaft 119. More particularly, the propeller shaft 119 includes an annular groove 175 which receives one leg 177 of a bellcrank lever which forms a part of a mechanical actuating linkage and which is pivotally mounted to the lower unit housing 115. The other end or leg 181 of the bellcrank lever 179 is connected to a pushrod or actuating link 183 such as has been commonly employed in the past to control clutch operation.

In this last regard, shifting of the clutch mechanism 161 in coordination with the axial movement of the propeller shaft 119 is afforded by means of one or more dogs or lugs 185 which are fixed to the propeller shaft 119 and which, in response to axial propeller shaft movement, are selectively positionable in a first or forward drive position (FIG. 5) drivingly engaging the bevel gear 163 to the propeller shaft 119 a second or rearward position (FIG. 6) drivingly engaging the bevel gear 165 to the propeller shaft 119, and a third or intermediate position wherein the dogs 185 are out of engagement with both bevel gears 163 and 165 and the drive is in neutral.

As in the embodiment shown in FIG. 1, the lower unit discharge port and the propeller hub 129 are provided with means for preventing the escape of exhaust gas when the propeller hub 129 and the lower unit discharge port are telescopically related. While various arrangements can be employed, in the disclosed construction such means is in the series of annular oppositely facing grooves 151 on the inner wall of the lower unit discharge port 125 and on the outer wall of the propeller hub 129.

In operation, when the actuating link 183 is displaced upwardly from the position shown in FIG. 5, the propeller shaft 1 19 is displaced to the right, thereby disengaging the dogs 185 from the bevel gear 163 to provide a neutral position wherein neither of the bevel gears 163 and is drivingly connected to the propeller shaft 119. Such rearward movement of the propeller shaft 119 also serves to at least partially withdraw the propeller hub 129 from telescopic relation to the lower unit discharge port 125.

Further upward movement of the actuating link 183 serves to displace the propeller shaft sufficiently rearwardly so as to engage the dogs with the bevel gear 165, thereby providing a rearward drive condition. Such rearward movement of the propeller shaft 119 also serves to separate the propeller hub 129 from the lower unit discharge port 128 so as to provide an annular exhaust gas outlet 137 forwardly of the propeller blades 131.

Shown in FIGS. 7 and 8 is still another embodiment of the invention, which embodies an axially shiftable propeller shaft 219 and which is similar to the embodiments of FIGS. 5 and 6 except that the propeller shifting is accomplished by a hydraulic actuator. Mere particularly, in the embodiment shown in FIGS. 5, 7, and 8, the propeller shaft 219 is biased forwardly by suitable means into the forward drive position and into engagement with a hydraulic actuator 291 which serves both to effect shifting of the clutch mechanisms 161 and selective location of the propeller hub 29 relative to the lower unit exhaust gas discharge port 25. Various arrangements can be employed to provide the propeller shaft biasing means. In the disclosed construction, there is employed a helical spring 293 contained between a snap ring 295 mounted on the propeller shaft 219 and a seat 297 adjacent to a shoulder on a propeller bearing support member 273. The disclosed biasing means provides the disclosed device with a fail-safe feature. Specifically, in the event of loss of hydraulic pressure in the actuator 291, the spring 293 will serve to assure that the drive is in forward position.

Various hydraulic actuators can be employed. In the disclosed construction, the actuator 291 includes a piston 299 having a stub shaft 201 which is rounded at its rearward end and engaged against the forward end of the propeller shaft 219 to facilitate rotation of the propeller shaft 219 relative thereto with a minimum of friction. The specific details of the hydraulic actuator are not believed to be a part of this invention, except to the extent that the actuator should be capable of affording piston movement sufficient to effect axial propeller shaft movement either merely to displace the propeller between forward and rearward positions or to accommodate shifting through forward, rearward and neutral conditions, in addition to affording propeller movement. Reference is hereby made to my corresponding application Ser. No. 627,106 filed Mar. 30, 1967 for one hydraulic actuator or mechanism which can be employed.

Various other arrangements can be employed to obtain at least some of the advantages of the invention by affording means for discharging exhaust gases forwardly of the propeller blades and into the water when operating in reverse drive. For instance, mechanically operated ports could be formed in the lower housing and subject to opening upon the reverse drive engagement in order to afford escape beneath water level of the exhaust gases in an area forwardly of the rearward and of the propeller and preferably forwardly of the propeller blades.

lclaim:

l. A marine propulsion device comprising a lower unit including a vertically extending drive shaft having a driving pinion, an axially shiftable, rotatably mounted propeller shaft, a pair of gears meshed with said pinion and rotatably mounted in spaced relation to each other coaxially with said propeller shaft, dog means fixed on said propeller shaft and located between said pair of gears for selective engagement with said gears in response to axial shifting of said propeller shaft to afford selective rotation of said propeller shaft by said drive shaft in forward and rearward drives, means for axially shifting said propeller shaft relative to said lower unit between a first position wherein said dog means is engaged with one of said gears to afford forward drive and a second position wherein said dog means is engaged with the other of said gears to afford reverse drive, and means yieldably biasing said propeller shaft into said forward drive position. p

2. A devicein accordance with claim 1 wherein said means for axially shifting said propeller shaft comprises a mechanical linkage.

3. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft includes'a hydraulic actuator.

4. A device in accordance with claim 3 wherein said means yieldably biasing said propeller shaft into said forward drive position also biases said propeller shaft into engagement with said hydraulic actuator.

5. A device in accordance with claim 1 wherein said biasing means includes a helical spring located in telescopic relation to the outer surface of said propeller shaft.

6. A device in accordance with claim 5 wherein said biasing means includes a shoulder on said propeller shaft, a seat on said lower unit at least partially surrounding said propeller shaft, and wherein said spring is engaged against said shoulder and said seat.

7. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft is located forwardly of said gears and said means for yieldably biasing said propeller shaft is located rearwardly of said gears.

8. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft relative to said lower unit is located forwardly of said gears and includes a hydraulic actuator located for engagement with said propeller shaft and wherein said means for yieldably biasing said propeller shaft is located rearwardly of said gears and includes a shoulder on said propeller shaft, a seat on said lower unit at least partially surrounding said propeller shaft, and a helical spring located in telescopic relation to the outer surface of said propeller shaft and engaged against said shoulder and said seat. 

1. A marine propulsion device comprising a lower unit including a vertically extending drive shaft having a driving pinion, an axially shiftable, rotatably mounted propeller shaft, a pair of gears meshed with said pinion and rotatably mounted in spaced relation to each other coaxially with said propeller shaft, dog means fixed on said propeller shaft and located between said pair of gears for selective engagement with said gears in response to axial shifting of said propeller shaft to afford selective rotation of said propeller shaft by said drive shaft in forward and rearward drives, means for axially shifting said propeller shaft relative to said lower unit between a first position wherein said dog means is engaged with one of said gears to afford forward drive and a second position wherein said dog means is engaged with the other of said gears to afford reverse drive, and means yieldably biasing said propeller shaft into said forward drive position.
 2. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft comprises a mechanical linkage.
 3. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft includes a hydraulic actuator.
 4. A device in accordance with claim 3 wherein said means yieldably biasing said propeller shaft into said forward drive position also biases said propeller shaft into engagement with said hydraulic actuator.
 5. A device in accordance with claim 1 wherein said biasing means includes a helical spring located in telescopic relation to the outer surface of said propeller shaft.
 6. A device in accordance with claim 5 wherein said biasing means includes a shoulder on said propeller shaft, a seat on said lower unit at least partially surrounding said propeller shaft, and wherein said spring is engaged against said shoulder and said seat.
 7. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft is located forwardly of said gears and said means for yieldably biasing said propellEr shaft is located rearwardly of said gears.
 8. A device in accordance with claim 1 wherein said means for axially shifting said propeller shaft relative to said lower unit is located forwardly of said gears and includes a hydraulic actuator located for engagement with said propeller shaft and wherein said means for yieldably biasing said propeller shaft is located rearwardly of said gears and includes a shoulder on said propeller shaft, a seat on said lower unit at least partially surrounding said propeller shaft, and a helical spring located in telescopic relation to the outer surface of said propeller shaft and engaged against said shoulder and said seat. 